Antibacterial cleansing compositions are typically used to cleanse the arms and hands of the user and to destroy bacteria and any other microorganisms which might be present on the user's arms or hands. These compositions are widely used in the health care industry by hospital staff and other health care personnel as hand washing cleansers to prevent nosocomial infections. They are particularly suitable for use by hospital personnel such as surgeons, nurses and other health care professionals who might be subject to contact with bacteria and the like. They are also suitable for use by personnel in the food service and meat processing industries and, generally are used for antimicrobial cleansing of the hands and arms by the public.
There are several active antimicrobial agents currently available for use in cleansing compositions. For example, many antimicrobial cleansing compositions contain a bisbiguanide bacterial substance such as chlorhexidine digluconate (CHG). Other cleansing compositions use phenolic compounds. The antimicrobial activity of these substances, however, are often dependent upon the type(s) of surfactants or other ingredients employed therewith, and therefore, the use of the same ingredients with these antimicrobial substances will not necessary derive the same result. For instance, in pending U.S. patent application Ser. No. 246,956 owned by the assignee of record, CHG is employed as the active antimicrobial agent. The cleansing compositions in that application include alkyl polyglucosides and nonionic alcohol ethoxylates as the primary surfactants. However, in compositions containing substituted phenols such as PCMX as the active antimicrobial agent, most of the nonionic alcohol ethoxylates inhibit, rather than enhance, the antibacterial activity of the active agent.
Heretofore, antimicrobial cleansing compositions containing substituted phenols as the active antimicrobial agent have also included anionic detergents, soaps, surfactants, and the like, as well as other compounds (nonionic ethoxylated surfactants, polyethylene glycol etc.) which are known to substantially reduce the antibacterial activity of the phenolic compounds. For example, Winicov et al. U.S. Pat. No. 3,824,190 and its subsequent Reissue Pat. No. Re. 28,778 both disclose the use of substituted phenolic compounds and anionic, surface active detergents or soaps in an alcohol and water-based carrier. Additionally, chelating agents such as ethylenediaminetetraacetic acid (hereinafter, EDTA) were also added.
Similarly, Garabedian et al. U.S. Pat. No. 4,632,772 discloses an antimicrobial composition which is said to exhibit excellent mildness characteristics and which includes a substituted phenol, namely PCMX, an anionic detergent, a thickener such as ethylene glycol monostearate, and a foam builder such as a fatty acid alkanol amide. The thickener and fatty acid alkanol amides as well as the anionic surfactant hinder the antibacterial activity of the phenolic compound.
In addition, Corti et al. U.S. Pat. No. 5,114,978 discloses anhydrous blends of PCMX in surfactant mixtures. More particularly, White teaches a method for solubilizing PCMX in high concentrations of water or aqueous compositions. The compositions include PCMX, diethanolamides of fatty acids and anionic surfactants of the class diethanolammonium salts of alkylpolyoxyethylsulfuric acid. Again, anionic surfactants and fatty acid amides which have been reported to inhibit the antimicrobial activity of the phenolic compound are used in the composition.
Finally, White U.S. Pat. No. 5,288,486 relates to alcohol-based antimicrobial compositions including PCMX or CHG, hydropropyl cellulose, an alcohol, an emollient, and water. The use of alcohol as a solvent or carrier in the composition is known to defat the skin which may lead to skin dryness and irritation.
Substituted phenols and particularly, para-chloro-meta-xylenol (PCMX) have been used for decades in Europe and more recently in the United States as an active ingredient in antiseptics and hand washing agents for health care personnel. PCMX, also listed in the Merck Index as 4-chloro-3,5-dimethyl phenol, is a substituted phenol having the structure ##STR1## and is reported to have 60 times the antimicrobial activity of phenol against a wide spectrum of bacteria. Moreover, PCMX has been reported to yield high initial reductions of Gram-positive and Gram-negative bacteria as well as fungi, and also to provide good residual activity for several hours between hand washings.
Thus, the use of a substituted phenol such as PCMX as an active antimicrobial agent in a cleansing composition would appear to be well known. Typically, where PCMX is used in cleansing compositions, it is used in concentrations of from about 0.1 to 4 percent by weight. However, the majority of formulas contain 1 percent or less by weight.
Unfortunately, as discussed briefly hereinabove, like that of chlorohexidene digluconate (CHG), the efficacy of PCMX and other substituted phenols against microorganisms is highly dependent upon the carrier and other chemical constituents of the antimicrobial cleanser. For instance, it has been reported that the antimicrobial activity of PCMX is potentiated against Pseudomonas aeruginosa by the addition of the chelating agent ethylenediaminetetraacetic acid (EDTA) and/or the sequestering agent sodium hexametaphosphate, presumably due to bonding of the agents to metal ions in the cell wall. On the other hand, the antimicrobial activity of PCMX has been reported to be reduced in the presence of organic material, and may be inhibited by moderate concentrations of anionic surfactants. Antimicrobial activity is also lost as a consequence of reversible interactions between PCMX and noninonic surfactants, polyethylene glycol, and polyethylene glycol stearate. Similarly, reduction in the antibacterial efficacy of PCMX has also been found to be the direct result of its interaction with a variety of macromolecules, namely, methyl cellulose, polyethylene glycol 6000, and polysorbate 80. The importance of these chemical and biochemical interactions cannot be over-stated because they determine the biocidal effectiveness of PCMX in hand washing formulations and other antimicrobial products.
Accordingly, the need exists for an antibacterial composition containing a substituted phenol as the active antimicrobial ingredient therein, which is suitably effective for killing bacteria and other microorganisms, but which does not include conventional anionic surfactants or other chemical ingredients known to be detrimental to the antimicrobial activity of the substituted phenol. That is, the desired cleansing composition should include surfactants and carriers which do not significantly effect the antimicrobial activity of the substituted phenol.